


Knock knock, let the devil in

by rexdaemoniorum



Category: Supernatural, Venom (Movie 2018)
Genre: Crossover, Gen, Sam Winchester Has A Symbiote, Sam Winchester's Demonic Powers, Season/Series 04
Language: English
Status: Completed
Published: 2019-02-05
Updated: 2019-02-05
Packaged: 2019-10-20 07:56:13
Rating: General Audiences
Warnings: Creator Chose Not To Use Archive Warnings
Chapters: 1
Words: 2,707
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/17618501
Author URL: https://archiveofourown.org/users/rexdaemoniorum/pseuds/rexdaemoniorum
Summary: After returning from Hell, Dean decides to confront Sam about the concerning use of his demonic powers.But as of recently, Sam’s got other powers that Dean ought to know about.SPN/Venom crossover beta’d with the help of @monicawoe !





	Knock knock, let the devil in

**Author's Note:**

  * For [smolstiel](https://archiveofourown.org/users/smolstiel/gifts).



 

“You were whoring it up with Ruby, Sam! You were doing God knows what with her! She’s a _demon_ , Sam, she’s trying to get into your head and you’re letting her!”

 

_I got there first_ , the voice sneered inside Sam’s head. He shook it off and took to defending himself- not a very common occurrence. “She’s helping me learn to use my powers for good.” His voice wobbled as he spoke, nearly giving away that he was doubting himself.

 

“She’s trying to get you to think using your powers is a safe thing to do! The visions I get, I was okay with those, b-but the mind shit? That’s sketchy! What’s next?”

 

_Oh, does he want to see what we’re capable of?_ It spoke again. Sam inhaled deeply to try and sway control from it. But he could feel his fingers, his knuckles, tightening and straining against his own synapses.

 

But he and the thing within had already bonded. There was nothing wrestling control from him. The thoughts were just as much his as they were the creature’s. “Why don’t you trust me?” Sam asked, this time purposefully utilizing his sensitivity and emotion. He figured it was too late to appeal to Dean as an equal. He was already seen as a threat- as if his brother could see right through him— or into him.

 

“Because you’ve got something in you, Sam!” The statement itself wasn’t new; he knew Dean was referring to the demon blood in his veins. “You’re a ticking time bomb! You said it yourself, you’re a-a.. you’re a ‘whole new level of _freak_!’”

 

The last word seemed to set off a spark within Sam.

 

_Oh- that’s my cue!_

 

Quick as a whip, Sam felt himself lunging towards Dean, grabbing him by the throat and pinning him to the wall. Both of them looked down and took in the frightening sight of Sam’s arm.

 

From up to the shoulder, it had been consumed in a thick, dark sludge that hardened over his skin. At his neck, Dean could feel that Sam’s fingers had extended into claws, just centimeters away from piercing his throat. He looked back up at his younger brother as if to say something, but felt his heart leap at the realization that his eyes were yellow.

 

Not even yellow irises, like the demon Azazel- they were _completely_ yellow, and far too big for his face.

 

“ **Damn right,** ” A deep, monstrous voice rumbled from Sam’s snarling mouth.

 

“Sam, what the fuck has gotten int—“ Dean could barely speak with the giant muscled arm almost crushing his windpipe. “What is this..?” He wheezed, feeling his face turn red. The viscous sludge rapidly grew until it consumed his brother entirely, doubling in size and transforming Sam into a hulking, rippling form with two glazed yellow eyes and a smile full of razor sharp teeth.

 

“ **You know, Dean, right now I’m feeling especially tempted to just** **_bite your head off_ ** **.** ” It leaned in close, its hot breath making sweat form on Dean’s face. “.. **But I know you’ll taste rotten. So why don’t you pretend that it’s** **_mercy_ ** **that keeps me from making a meal out of you?** ”

 

Dean could barely believe what he was seeing. It wasn’t even a stretch to believe he was still in Hell. But in the event that he was finally back on Earth, what in the world did Sam go through?

 

* * *

 

 

Sam stepped slowly and carefully along the floorboards of the old house, his shoes occasionally sticking from the aged puddles of blood.

 

“Do you even know what this thing is?” Ruby whispered, disturbing his idea of moving through the place silently.

 

“Do you?” Sam hissed back at her. She glared at him like talking back was a crime, and he’d become a repeat offender as of lately.

 

“Sam, you’re getting more and more reckless with your cases,” she cautioned him as they crept along the hallway. “A couple months ago, you wouldn’t have done this until you properly identified the-“

 

“ _Ooh, people_ ! _Finally!_ ” A voice sounded from somewhere inside the house. It was dark, guttural, and beyond anything Sam (or even Ruby) had ever heard. “ _C’mere, c’mere, c’mere_..” it crooned, as large footsteps thudded and shook the foundation of the house.

 

Sam and Ruby exchanged puzzled glances before turning towards the stairwell, where a disheveled older woman nearly tumbled down the stairs in her attempt to flee. Sam rushed to the poor lady’s side, inspecting the multiple cases of rot splotching various parts of her body.

 

“Ma’am, are y- what’s going on? Are you in danger?”

 

“I’d say we’re far beyond _danger_ ,” Ruby mumbled loud enough for them to hear. A brief glance from Sam and she turned in the opposite direction.

 

“It’s- this thing is—,” the lady appeared to be choking on her own spit as she spoke. She heaved in his arms and grabbed onto him with white knuckles. Sam leaned as far back as he could without seeming like he was trying to keep his distance. Ruby, however, was probably one second away from pulling him away for his own sake.

 

“What’s up there, ma’am? What does it look like?”

 

Her eyes nearly bugged out of her head and she thrashed once more before letting go of him and pointing to herself. Then, with a nauseating _squelch_ , the lady coughed up a copious amount of blood mixed with an unknown black substance before tumbling out of his arms and falling still.

 

Sam scrambled back, nearly taking Ruby’s legs out from under her when the poor woman died.

 

“W- is this croatoan? Maybe some.. mutated form of..” he began.

 

“Doubt it,” Ruby cut him off. “Sam, this isn’t one of the seals. I promise you that. Which means it’s not our business. Let’s go.”

 

She took his hand and brought him to his feet before he hesitantly started to walk out with her, unaware of what had hitched a ride while he had his back turned.

 

* * *

 

 

Sam could smell Ruby’s blood from across the motel room. Usually it was only when she was wounded or deliberately letting him drink, but this time it was unbearable. It was driving him crazy. He sucked in lungfuls of air in order to clear his mind, but he couldn’t push away the thought. He stood up from the bed, somehow navigating his way to her despite his head spinning.

 

“Ruby, I need it. I need it now—“ he mumbled almost unintelligibly as he staggered towards her. She turned just in time to see him come close and almost fall onto her, and managed to hold him back at arms’ length.

 

“H-hey, Sam..!” She tried to look clearly into his eyes, but his hair was damp and hanging lowly over his brow like a mop. He was also so sweaty she could barely keep a steady grip on him. She’d figured it was blood he was craving, albeit so suddenly, but began to second-guess the idea when he began to snap at her with his jaws. His teeth were coming dangerously close to her face. She was thinking he wanted blood; he was acting like he wanted to bite her head off. “Sam, get _back!”_  She gathered enough space and momentum to throw him off, knocking him onto the floor and clumsily stepping over him. Then, she grabbed his wrist, which was warm to the touch.

 

“Sam, you’re burning up. I’m not sure what the fuck’s gotten into you, but you gotta cool off.” Luckily for her, it seemed he’d run out of all his energy and couldn’t put up a fight. She dragged him across the floor and into the bathroom, briefly dropping him like trash to turn on the faucet. He let out a pained grunt when his head hit the floor.

 

“Whoops, my bad,” she mumbled over the running water. When it was up about two inches, she pulled him up and proceeded to dump him, fully-clothed, into the near-empty tub. His head was directly beneath the faucet, pouring cold water right onto his face.

 

Ruby watched him until his breathing slowed and he shifted around semi-consciously. She stopped the water right before it rose above his face, then put a hand under his head and lifted it up.

 

“Sam,” she whispered. “Sam..”

 

He slowly opened his eyes to look up at her.

 

“..Hey.”

 

“Sam, do you- do you need anything? Something to eat?”

 

“Mm- I tried looking for something.. to eat. All I found were the.. chocolates.”

 

“Chocolates?”

 

Sam nodded as quickly as he could, and the water stirred beneath him. “Yeah, the little.. little complimentary chocolates. They weren’t much, but they hit the spot.”

 

“Okay, well, maybe I can..” Ruby was drawing a blank. She gently laid him back down and stood up. “Maybe I can order something. But only if we’re _out of options_ do you get more blood, alright?”

 

“Mmuh,” Sam groaned just above the surface of the water. “That chocolate was good.”

  
_Sam doesn’t even like chocolate_ , Ruby thought.

 

* * *

 

 

Eventually, Ruby had pizza delivered. There were places nearby that probably got the orders done quicker and were overall tastier, but this one was one of those faux Italian places that also had French fries. Getting Sam fed was important, but not as much as that.

 

She set the two pies on the table and immediately opened up the bag of fries. Sam sat on the other side of the table, in nothing but a light T-shirt and sweatpants. He was always at his lowest point when he was in one layer.

 

By the time she’d opened the bag and eaten a couple fries, a considerable amount was already missing from one of the pizzas. She looked up to Sam, who was wolfing the slices down like his life depended on it.

 

“Slow down. Breathe,” she instructed him. He didn’t even spare her a glance.

 

In the next five minutes, he had gone through both boxes. She’d intended on having at least a couple slices, but.. apparently not.

 

“I think you caught whatever bug that crazy lady had.”

 

Sam was wiping the copious amounts of pizza grease off of his face with a napkin. He looked up as he got out of the chair. “What bug?” He came close and snatched a few fries out of the bag she ate from, and she slapped his hand away.

 

“That thing that woman coughed up. Maybe it was contagious.”

 

Sam wasn’t the type to doubt a legitimate concern. “Yeah, m-makes sense.” He fanned himself before looking her up and down and shifting uncomfortably where he stood.

 

“No, Sam,” she immediately caught on to what he was thinking. “I think you need to get some rest. You’re running on fumes.”

 

He shook his head like a wet dog and rubbed his face. “You know what, you’re right. I- I’m gonna.. try to sleep.” He flopped onto the bed behind her, twitching and shuffling before eventually drifting off.

 

At some point, Ruby had gone off to figure out what the hell Sam had gotten. Perhaps whatever intel she regularly relied on had an answer. She was probably in a hurry, given Sam’s concerning condition, so he didn’t have much time to figure it out without her looming over him.

 

He wasn’t sure what was going on at all. The woman he’d gotten it from gave no implications of what it was, but it was unlike anything he’d ever come in contact with.

 

He attempted to think straight and use his expansive knowledge of all-things-fucked-up to try and identify this strange ailment. While deep in thought, a voice made itself clear.

 

“ _Hey, Mr. Pretty Boy. You ever met a symbiote before?_ ”

 

Sam nearly jumped a foot in the air. This voice didn’t sound like it came from somewhere other than inside his head. It was also deep and guttural, like if an animal had somehow figured out language. Like the voice he and Ruby heard before the sick lady came down the stairs.

 

“A.. a what?”

 

“ _A symbiote, as your kind call us.”_ It spoke again. All of a sudden, a black, oozing substance began to manifest on his shoulder, stretching into a snake-like creature that craned itself over to face him. “ _Hi there._ ”

 

His jaw dropped at the sight of this thing sprouting from his body. He grabbed it with his other hand and attempted to yank it off, but it seemed to slip right through his grip.

 

“ _Ooh. Pretty grabby on the first date, huh?”_

 

“What are you? What is a ‘symbiote’?” He looked closely at its face. It was eel-like in appearance, with a mouth not big enough for all those teeth. Two horns curled over its little head. Its eyes were big and narrow, and yellow. That color wasn’t a favorite of Sam’s.

 

“ _From another planet. We can bond to hosts, as you can tell, giving the both of us tremendous strength, but..”_ It grinned its anglerfish smile at him. “ _As long as we got enough to eat._ ”

 

“So you’re an alien.”

 

_“..Yeah.”_

 

Sam couldn’t believe what he was hearing. “Alright. I’ll add that to my resume.”

 

“ _Now it’s your turn,.”_ It darted forward, like a snake about to strike. “ _What the hell are_ **_you_ **?”

 

Sam shrugged. “What do you mean?” His voice was hollow and embarrassingly ingenuine.

 

“ _I know you know what I mean. There’s something in you. You’re stronger than other humans. I could tell the second I hopped on.”_

 

“I.. I’ve got demon blood in me.” He answered hesitantly. The symbiote blinked its big, glazed eyes and seemingly nodded in response. “It gives me certain powers, but their strength relies on me consuming more of it.”

 

“ _Perfect!”_ The parasite responded in the cheeriest way a dark, throaty voice possibly could. “ _Let’s find some demons and eat up!”_

 

Sam raised his hands and waved them in protest. “No, y’see I-.. I do it to protect other humans. That means the humans they’re possessing, too. I can’t just eat them!”

 

“ _That’s no fun,”_ it mumbled. Even though Sam had barely come to know this extraterrestrial tapeworm for more than a couple days, he’d begun to grow attached to it. Maybe it could be useful in defeating Lilith.

 

“Well.. not all of them are using living vessels. Maybe- _maybe_ ,” he repeated very slowly to calm the symbiote as it began to wiggle in anticipation. “..you can have those. Okay?”

 

“ _Oh, yeah_ ,” it hissed. _“Chocolate’s good, too.”_

 

“Really? Oh, well that’s good to know..” Sam trailed off, keeping his unsteady gaze on the creature.

 

“ _I have a name, you know.”_ It said as if it were reading its mind.

 

“Okay, and that is?”

 

_“Freak,”_ it answered. Sam almost thought the symbiote was bluffing, like if its access to his body allowed it to dig up a word he’d already had a history with.

 

“Are you joking?”

 

_“Why would I be joking? That’s my name- Freak.”_

 

Sam couldn’t help but smile, even though the immediate thought didn’t make him very happy. “People call me that, sometimes.”

 

“ _Really? Well, then I think we’re a good match, Mr. Pretty Boy. Two halves of a whole freak.”_

 

“Uh, I have a name too. I’m Sam.”

 

_“..Naaah. Mr. Pretty Boy it is.”_

 

* * *

 

 

“Sam—,” Dean choked out pitifully. “What the hell is this? What happened to you?”

 

The creature’s face dematerialized on one side, revealing Sam underneath.

 

“We’re a team, now,” He grinned. “And from now on, any complaints or protests you have..” the thing resorbed him and ran a long, serpentine tongue over its teeth before finishing his sentence.

 

“ **..You can direct it to both of us.** ”

 

Dean flinched at the frightening sneer the Sam-creature had on its face. He gathered his breath and, for once, chose his words carefully before speaking again.

 

“What.. what have you done to my brother?” His voice cracked as he asked the question, trying his best to indicate submission and avoid being eaten. The thing released its grip in a flash and Dean dropped half a foot back onto the ground, feeling the impact shoot up his legs and making him stumble.

 

“ **Your brother is part of us** ,” it nodded, moving its shoulders as if it were stretching out its new muscles. _**“**_ **W** **e.. are** **_Freak.”_ **

**Author's Note:**

> This was an early birthday gift for @smolstiel , but I had so much fun making this!! I put a lot of work and thought into both the fic and the art. I hope you enjoyed it!


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